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Grand Cherokee with Engine Knock


 
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Shane4188
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Joined: 02 Apr 2006

PostPosted: Tue Aug 07, 2007 9:26 pm    Post subject: Grand Cherokee with Engine Knock Reply with quote

Hello,

I've got a 1993 Grand Cherokee Laredo that has the classic engine knock. It has been like this for as long as we have owned it with no problems caused (at least 100,000 miles). Is there a sensor or anything that you think might stop it from knocking? This knocking disappears completely past 1000 rpm. It has nothing to do with the grade of gasoline, I have tried all. Any input appreciated. Thanks,

Shane
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1fox2go
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Joined: 01 Dec 2004
Location: Fishersville, Virginia

PostPosted: Tue Aug 07, 2007 11:29 pm    Post subject: Reply with quote

Does it do it at idle right after start up?

fades as the engine gets warmer?
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96 Cherokee 7.5 inch TnT long arm Locked F/R, D44 rear, 4.56s, 35x12.50 Muds/36x12.50 TSLs
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cajzmere
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Joined: 19 Jul 2005
Location: Rochester, NY AKA NY Tundra.

PostPosted: Mon Aug 13, 2007 7:02 pm    Post subject: Reply with quote

Whenever I hear "knock", I think either detonation or bearings. If it's been doing this for that long,( I had a 4.0 Wrangler that did this for 215k miles) and no other symptoms, turn up your radio. Using hi test gas only works with "pinging", or sometimes "ticking". Knock sensors work by retarding spark advance(sorry, I'm old school) or spark pulse to stop premature detonation. Knocking is almost always mechanical, not sensor related. I wouldn't worry. Cool
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1fox2go
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Joined: 01 Dec 2004
Location: Fishersville, Virginia

PostPosted: Tue Aug 14, 2007 3:51 am    Post subject: Reply with quote

im pretty sure its just the "dieseling effect" as they call it. Almost everyone with a 4.0 complains about it
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96 Cherokee 7.5 inch TnT long arm Locked F/R, D44 rear, 4.56s, 35x12.50 Muds/36x12.50 TSLs
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cajzmere
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Joined: 19 Jul 2005
Location: Rochester, NY AKA NY Tundra.

PostPosted: Thu Aug 16, 2007 4:42 pm    Post subject: Reply with quote

Effin' valve rattle is what mine did, I tried everything I could think of and still couldn't get that "dieseling" to stop. 4.0L engines are designed to run exactly like tractor engines. Loose and sloppy, tons of torque, last forever.
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